Speaker A
This episode was made possible by generous supporters on Patreon. Hey, Crazies. I’ve done a video on solar panels, and I’ve done a video on batteries, but neither of those methods is how we generate most of our power.
Explore how magnetic induction generates most of our electricity, from Faraday's experiments to modern power sources like wind and nuclear.
Key Takeaways
- Magnetic induction is the fundamental principle behind most electricity generation.
- Faraday’s Law explains how changing magnetic fields induce voltage in coils.
- Electric generators are essentially motors run in reverse.
- Various energy sources (wind, water, steam) ultimately convert mechanical motion into electrical energy via induction.
- Understanding induction clarifies the physics behind common power generation technologies.
Summary
- Magnetic induction is the primary method for generating electricity worldwide.
- The concept dates back to Michael Faraday's experiments in 1831 involving coils and disks.
- Moving charges create magnetic fields, which can induce currents in nearby wires.
- Induction is reversible: moving a wire in a magnetic field induces current, similar to how current in a wire creates a magnetic force.
- Simple motors demonstrate this principle by spinning coils to generate voltage.
- Faraday's Law mathematically describes how changing magnetic flux induces voltage in coils.
- Modern electricity generation uses spinning coils in magnetic fields powered by wind, water, steam from fossil fuels, or nuclear reactors.
- Voltage is generated by the change in magnetic flux through coil loops, proportional to the number of loops and the magnetic field area.
- Despite being an old method, engineering advances have made magnetic induction highly efficient and scalable.
- Environmental impact varies depending on the energy source driving the coil rotation.
Chapters
- 00:00Introduction and Overview of Power Generation Methods
- 00:21Understanding Magnetic Induction
- 00:44Historical Context: Faraday's Experiments
- 01:00Magnetic Fields and Moving Charges
- 01:19Magnetic Force and Electromagnetic Interaction
- 01:33Reversibility of Magnetic Induction
- 01:49Inducing Current by Moving Wire
- 02:09Practical Limitations of Simple Induction
- 02:51Building and Understanding a Simple Motor
- 03:16Using a Motor as a Generator
Full Transcript — Download SRT & Markdown
Speaker A
So how do we generate most of our power? Magnetic induction! I’ve wanted to make this video for a long time.
Speaker A
Let’s do this! It seems natural to start with the name magnetic induction. The word induction comes from the root word induce, which just means to cause something by persuasion or influence.
Speaker A
In this case, magnetism induces electricity. This method of generating electricity isn’t anything new. I mean, it’s almost two centuries old.
Speaker A
To the timeline! All the way back in 1831, Michael Faraday was doing a series of experiments, some involving coils and others disks, but I’m getting a bit ahead of myself.
Speaker A
We can understand induction with something simpler than a coil. A current in a long straight wire will do.
Speaker A
Any moving charge generates a magnetic field. We call that an electromagnet. So let’s say we’ve got a long straight wire carrying an electric current.
Speaker A
Since current is moving charge, that wire will generate a magnetic field. If there’s another wire carrying another current inside of that field, it will be affected by that field.
Speaker A
In this case, the wire is pushed sideways. That push is a magnetic force, which is part of the electromagnetic force.
Speaker A
You can see here it requires the charge to be moving. Wait, how does all this relate to induction?
Speaker A
Patience, Question Clone. Patience. OK, sure, one current exerts a force on another using a magnetic field.
Speaker A
Nothing crazy there. But this process is completely reversible. If the current in a wire can be pushed sideways by a magnetic field, then pushing a wire sideways in a magnetic field should cause a current.
Speaker A
And that’s exactly what happens. That’s magnetic induction! We’ve induced a current through motion in a magnetic field.
Speaker A
That’s it? Well, yeah. I never said this was complicated. People make this out to be so magical sometimes, but it’s just about reversibility.
Speaker A
Moving charge in a wire this way gives us an effect that way. All we’ve done with induction is swap the arrows.
Speaker A
We moved the wire sideways to push the current along. They have to be perpendicular because cross products.
Speaker A
But the cool thing is, it doesn’t even matter which wire you move. A current will be induced in the second wire regardless.
Speaker A
While this setup gives us a simple understanding of induction, unfortunately, it’s not very practical.
Speaker A
AC wall sockets almost always operate at 50 to 60 Hz. That means I’d have to wiggle this wire back and forth 50 to 60 times per second, which is kind of ridiculous.
Speaker A
Hmm, what’s something else that cycles that we can reverse? What about an electric motor?
Speaker A
You know, that might actually work! We can build a simple motor using a battery, a magnet, some insulated wire, and a few other things just to hold it all together.
Speaker A
You wrap the wire into a coil and set it up so current will run through it.
Speaker A
All it needs is a little nudge to get started, and it’ll spin as long as it has energy from the battery.
Speaker A
Just like with the straight wire case, charge is moving through the coil wire inside a magnetic field, so there’s a force on it.
Speaker A
Now let’s put that thing down, flip it, and reverse it. [Gibberish] Work it. I need a glass of water.
Speaker A
Anyway, what happens if we remove the battery and just spin the coil by hand?
Speaker A
Doing this should induce a current, just like moving our wire did before. Well, at least if we have somewhere for that current to go.
Speaker A
What do you get if it’s just sitting there not connected to anything? A voltage!
Speaker A
That’s just energy per unit charge. It’s the energy the charges need to move forward to make a current, if they could.
Speaker A
In this case, you might not have a current yet, but there’s still a potential for one.
Speaker A
Get it? A potential? Because another name for voltage is electric potential? Never mind. The point is a simple electric generator is just a backwards motor.
Speaker A
Back in 1831, Faraday was generating voltage by moving coils around and spinning disks. We’ve just combined those ideas by spinning coils.
Speaker A
So how much voltage does it generate? Well, that depends. In order to make predictions about anything physics-related, we need an equation.
Speaker A
The concepts discovered by Faraday weren’t written mathematically until about 1885 when Oliver Heaviside properly unified electricity and magnetism.
Speaker A
That’s why the law describing magnetic induction is called Heaviside’s Law. Just kidding! It’s called Faraday’s Law.
Speaker A
I’d like to tell you it’s because Heaviside already had a bunch of stuff named after him like Laplace.
Speaker A
Unfortunately, that’s not true. Heaviside really got shafted here. But let’s try to read Faraday’s law in plain English.
Speaker A
On the left, there’s the result we’re looking for: a voltage. On the right, we’ve got the cause of that voltage: a change over time.
Speaker A
The N is just the number of loops in our coil. The Phi is the magnetic field on an area.
Speaker A
Also known as magnetic flux. The fact that it’s called flux isn’t important though. You know what? Forget I even mentioned it.
Speaker A
Our coil has maybe 10 loops in it, so N equals 10. Nice and easy.
Speaker A
The coil also forms a circular area, an area that has magnetic field inside it.
Speaker A
The field inside the area multiplied by the area itself is that Phi symbol. Then we multiply by 10 because there are 10 loops and BAM!
Speaker A
We’ve got a number we can use in Faraday’s law. That number changes because the loops are spinning.
Speaker A
Sometimes they have a lot of magnetic field inside them. Sometimes only a little bit.
Speaker A
Sometimes none. And, according to Faraday’s law, that change gives us a voltage. Our backwards motor transforms the energy from my hand into electrical energy.
Speaker A
Of course, turning this by hand is a lot of work I’d rather not do.
Speaker A
Having hamsters or clones running in wheels would be less work for me, but that’s not very scalable.
Speaker A
This method might be 200 years old, but we’ve gotten a lot better at engineering it.
Speaker A
So how do we generate most of our power? By making coils spin inside magnetic fields.
Speaker A
Wind power? The wind turns the blades, which are attached to a coil. Water power?
Speaker A
The flowing water turns a coil. Coal or natural gas? The heat from burning it boils water into steam.
Speaker A
The steam turns a coil. Nuclear? The heat from the reactor boils water into steam.
Speaker A
The steam turns a coil. In every case, we’re using a magnetic field to transform some other energy into useful electrical energy.
Speaker A
Most of our electrical energy is made through magnetic induction. It’s just that some source energies are better for the environment than others.
Speaker A
So, did this clear up any misconceptions you had about induction? Let us know in the comments.
Speaker A
Thanks for liking and sharing this video. Don’t forget to subscribe if you’d like to keep up with us.
Speaker A
And until next time, remember, it’s OK to be a little crazy. If phosphorus is so great for solar panels, why not just use that and forget about the silicon?
Speaker A
That would change how the atoms bond to each other and what energy levels they have.
Speaker A
We want there to be only four bonds, and we need the gap to be the size of a photon of visible light.
Speaker A
You’re not getting that with just phosphorus. OK, Crazies, thanks for watching!
Topics:magnetic inductionFaraday's Lawelectricity generationelectromagnetismelectric generatormagnetic fieldelectric motorrenewable energywind powersteam power
